1 files changed, 144 insertions, 133 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index 83293be..23702a9 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -67,33 +67,43 @@ struct dentry_stat_t dentry_stat = {
 	.age_limit = 45,
 };
 
-static void __d_free(struct dentry *dentry)
+static struct percpu_counter nr_dentry __cacheline_aligned_in_smp;
+static struct percpu_counter nr_dentry_unused __cacheline_aligned_in_smp;
+
+#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
+int proc_nr_dentry(ctl_table *table, int write, void __user *buffer,
+		   size_t *lenp, loff_t *ppos)
+{
+	dentry_stat.nr_dentry = percpu_counter_sum_positive(&nr_dentry);
+	dentry_stat.nr_unused = percpu_counter_sum_positive(&nr_dentry_unused);
+	return proc_dointvec(table, write, buffer, lenp, ppos);
+}
+#endif
+
+static void __d_free(struct rcu_head *head)
 {
+	struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
+
 	WARN_ON(!list_empty(&dentry->d_alias));
 	if (dname_external(dentry))
 		kfree(dentry->d_name.name);
 	kmem_cache_free(dentry_cache, dentry); 
 }
 
-static void d_callback(struct rcu_head *head)
-{
-	struct dentry * dentry = container_of(head, struct dentry, d_u.d_rcu);
-	__d_free(dentry);
-}
-
 /*
- * no dcache_lock, please.  The caller must decrement dentry_stat.nr_dentry
- * inside dcache_lock.
+ * no dcache_lock, please.
  */
 static void d_free(struct dentry *dentry)
 {
+	percpu_counter_dec(&nr_dentry);
 	if (dentry->d_op && dentry->d_op->d_release)
 		dentry->d_op->d_release(dentry);
+
 	/* if dentry was never inserted into hash, immediate free is OK */
 	if (hlist_unhashed(&dentry->d_hash))
-		__d_free(dentry);
+		__d_free(&dentry->d_u.d_rcu);
 	else
-		call_rcu(&dentry->d_u.d_rcu, d_callback);
+		call_rcu(&dentry->d_u.d_rcu, __d_free);
 }
 
 /*
@@ -123,37 +133,34 @@ static void dentry_iput(struct dentry * dentry)
 }
 
 /*
- * dentry_lru_(add|add_tail|del|del_init) must be called with dcache_lock held.
+ * dentry_lru_(add|del|move_tail) must be called with dcache_lock held.
  */
 static void dentry_lru_add(struct dentry *dentry)
 {
-	list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
-	dentry->d_sb->s_nr_dentry_unused++;
-	dentry_stat.nr_unused++;
-}
-
-static void dentry_lru_add_tail(struct dentry *dentry)
-{
-	list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
-	dentry->d_sb->s_nr_dentry_unused++;
-	dentry_stat.nr_unused++;
+	if (list_empty(&dentry->d_lru)) {
+		list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
+		dentry->d_sb->s_nr_dentry_unused++;
+		percpu_counter_inc(&nr_dentry_unused);
+	}
 }
 
 static void dentry_lru_del(struct dentry *dentry)
 {
 	if (!list_empty(&dentry->d_lru)) {
-		list_del(&dentry->d_lru);
+		list_del_init(&dentry->d_lru);
 		dentry->d_sb->s_nr_dentry_unused--;
-		dentry_stat.nr_unused--;
+		percpu_counter_dec(&nr_dentry_unused);
 	}
 }
 
-static void dentry_lru_del_init(struct dentry *dentry)
+static void dentry_lru_move_tail(struct dentry *dentry)
 {
-	if (likely(!list_empty(&dentry->d_lru))) {
-		list_del_init(&dentry->d_lru);
-		dentry->d_sb->s_nr_dentry_unused--;
-		dentry_stat.nr_unused--;
+	if (list_empty(&dentry->d_lru)) {
+		list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
+		dentry->d_sb->s_nr_dentry_unused++;
+		percpu_counter_inc(&nr_dentry_unused);
+	} else {
+		list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
 	}
 }
 
@@ -172,7 +179,6 @@ static struct dentry *d_kill(struct dentry *dentry)
 	struct dentry *parent;
 
 	list_del(&dentry->d_u.d_child);
-	dentry_stat.nr_dentry--;	/* For d_free, below */
 	/*drops the locks, at that point nobody can reach this dentry */
 	dentry_iput(dentry);
 	if (IS_ROOT(dentry))
@@ -237,13 +243,15 @@ repeat:
 		if (dentry->d_op->d_delete(dentry))
 			goto unhash_it;
 	}
+
 	/* Unreachable? Get rid of it */
  	if (d_unhashed(dentry))
 		goto kill_it;
-  	if (list_empty(&dentry->d_lru)) {
-  		dentry->d_flags |= DCACHE_REFERENCED;
-		dentry_lru_add(dentry);
-  	}
+
+	/* Otherwise leave it cached and ensure it's on the LRU */
+	dentry->d_flags |= DCACHE_REFERENCED;
+	dentry_lru_add(dentry);
+
  	spin_unlock(&dentry->d_lock);
 	spin_unlock(&dcache_lock);
 	return;
@@ -318,11 +326,10 @@ int d_invalidate(struct dentry * dentry)
 EXPORT_SYMBOL(d_invalidate);
 
 /* This should be called _only_ with dcache_lock held */
-
 static inline struct dentry * __dget_locked(struct dentry *dentry)
 {
 	atomic_inc(&dentry->d_count);
-	dentry_lru_del_init(dentry);
+	dentry_lru_del(dentry);
 	return dentry;
 }
 
@@ -441,73 +448,27 @@ static void prune_one_dentry(struct dentry * dentry)
 
 		if (dentry->d_op && dentry->d_op->d_delete)
 			dentry->d_op->d_delete(dentry);
-		dentry_lru_del_init(dentry);
+		dentry_lru_del(dentry);
 		__d_drop(dentry);
 		dentry = d_kill(dentry);
 		spin_lock(&dcache_lock);
 	}
 }
 
-/*
- * Shrink the dentry LRU on a given superblock.
- * @sb   : superblock to shrink dentry LRU.
- * @count: If count is NULL, we prune all dentries on superblock.
- * @flags: If flags is non-zero, we need to do special processing based on
- * which flags are set. This means we don't need to maintain multiple
- * similar copies of this loop.
- */
-static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags)
+static void shrink_dentry_list(struct list_head *list)
 {
-	LIST_HEAD(referenced);
-	LIST_HEAD(tmp);
 	struct dentry *dentry;
-	int cnt = 0;
 
-	BUG_ON(!sb);
-	BUG_ON((flags & DCACHE_REFERENCED) && count == NULL);
-	spin_lock(&dcache_lock);
-	if (count != NULL)
-		/* called from prune_dcache() and shrink_dcache_parent() */
-		cnt = *count;
-restart:
-	if (count == NULL)
-		list_splice_init(&sb->s_dentry_lru, &tmp);
-	else {
-		while (!list_empty(&sb->s_dentry_lru)) {
-			dentry = list_entry(sb->s_dentry_lru.prev,
-					struct dentry, d_lru);
-			BUG_ON(dentry->d_sb != sb);
+	while (!list_empty(list)) {
+		dentry = list_entry(list->prev, struct dentry, d_lru);
+		dentry_lru_del(dentry);
 
-			spin_lock(&dentry->d_lock);
-			/*
-			 * If we are honouring the DCACHE_REFERENCED flag and
-			 * the dentry has this flag set, don't free it. Clear
-			 * the flag and put it back on the LRU.
-			 */
-			if ((flags & DCACHE_REFERENCED)
-				&& (dentry->d_flags & DCACHE_REFERENCED)) {
-				dentry->d_flags &= ~DCACHE_REFERENCED;
-				list_move(&dentry->d_lru, &referenced);
-				spin_unlock(&dentry->d_lock);
-			} else {
-				list_move_tail(&dentry->d_lru, &tmp);
-				spin_unlock(&dentry->d_lock);
-				cnt--;
-				if (!cnt)
-					break;
-			}
-			cond_resched_lock(&dcache_lock);
-		}
-	}
-	while (!list_empty(&tmp)) {
-		dentry = list_entry(tmp.prev, struct dentry, d_lru);
-		dentry_lru_del_init(dentry);
-		spin_lock(&dentry->d_lock);
 		/*
 		 * We found an inuse dentry which was not removed from
 		 * the LRU because of laziness during lookup.  Do not free
 		 * it - just keep it off the LRU list.
 		 */
+		spin_lock(&dentry->d_lock);
 		if (atomic_read(&dentry->d_count)) {
 			spin_unlock(&dentry->d_lock);
 			continue;
@@ -516,13 +477,60 @@ restart:
 		/* dentry->d_lock was dropped in prune_one_dentry() */
 		cond_resched_lock(&dcache_lock);
 	}
-	if (count == NULL && !list_empty(&sb->s_dentry_lru))
-		goto restart;
-	if (count != NULL)
-		*count = cnt;
+}
+
+/**
+ * __shrink_dcache_sb - shrink the dentry LRU on a given superblock
+ * @sb:		superblock to shrink dentry LRU.
+ * @count:	number of entries to prune
+ * @flags:	flags to control the dentry processing
+ *
+ * If flags contains DCACHE_REFERENCED reference dentries will not be pruned.
+ */
+static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags)
+{
+	/* called from prune_dcache() and shrink_dcache_parent() */
+	struct dentry *dentry;
+	LIST_HEAD(referenced);
+	LIST_HEAD(tmp);
+	int cnt = *count;
+
+	spin_lock(&dcache_lock);
+	while (!list_empty(&sb->s_dentry_lru)) {
+		dentry = list_entry(sb->s_dentry_lru.prev,
+				struct dentry, d_lru);
+		BUG_ON(dentry->d_sb != sb);
+
+		/*
+		 * If we are honouring the DCACHE_REFERENCED flag and the
+		 * dentry has this flag set, don't free it.  Clear the flag
+		 * and put it back on the LRU.
+		 */
+		if (flags & DCACHE_REFERENCED) {
+			spin_lock(&dentry->d_lock);
+			if (dentry->d_flags & DCACHE_REFERENCED) {
+				dentry->d_flags &= ~DCACHE_REFERENCED;
+				list_move(&dentry->d_lru, &referenced);
+				spin_unlock(&dentry->d_lock);
+				cond_resched_lock(&dcache_lock);
+				continue;
+			}
+			spin_unlock(&dentry->d_lock);
+		}
+
+		list_move_tail(&dentry->d_lru, &tmp);
+		if (!--cnt)
+			break;
+		cond_resched_lock(&dcache_lock);
+	}
+
+	*count = cnt;
+	shrink_dentry_list(&tmp);
+
 	if (!list_empty(&referenced))
 		list_splice(&referenced, &sb->s_dentry_lru);
 	spin_unlock(&dcache_lock);
+
 }
 
 /**
@@ -538,7 +546,7 @@ static void prune_dcache(int count)
 {
 	struct super_block *sb, *p = NULL;
 	int w_count;
-	int unused = dentry_stat.nr_unused;
+	int unused = percpu_counter_sum_positive(&nr_dentry_unused);
 	int prune_ratio;
 	int pruned;
 
@@ -608,13 +616,19 @@ static void prune_dcache(int count)
  * shrink_dcache_sb - shrink dcache for a superblock
  * @sb: superblock
  *
- * Shrink the dcache for the specified super block. This
- * is used to free the dcache before unmounting a file
- * system
+ * Shrink the dcache for the specified super block. This is used to free
+ * the dcache before unmounting a file system.
  */
-void shrink_dcache_sb(struct super_block * sb)
+void shrink_dcache_sb(struct super_block *sb)
 {
-	__shrink_dcache_sb(sb, NULL, 0);
+	LIST_HEAD(tmp);
+
+	spin_lock(&dcache_lock);
+	while (!list_empty(&sb->s_dentry_lru)) {
+		list_splice_init(&sb->s_dentry_lru, &tmp);
+		shrink_dentry_list(&tmp);
+	}
+	spin_unlock(&dcache_lock);
 }
 EXPORT_SYMBOL(shrink_dcache_sb);
 
@@ -632,7 +646,7 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
 
 	/* detach this root from the system */
 	spin_lock(&dcache_lock);
-	dentry_lru_del_init(dentry);
+	dentry_lru_del(dentry);
 	__d_drop(dentry);
 	spin_unlock(&dcache_lock);
 
@@ -646,7 +660,7 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
 			spin_lock(&dcache_lock);
 			list_for_each_entry(loop, &dentry->d_subdirs,
 					    d_u.d_child) {
-				dentry_lru_del_init(loop);
+				dentry_lru_del(loop);
 				__d_drop(loop);
 				cond_resched_lock(&dcache_lock);
 			}
@@ -703,20 +717,13 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
 			 * otherwise we ascend to the parent and move to the
 			 * next sibling if there is one */
 			if (!parent)
-				goto out;
-
+				return;
 			dentry = parent;
-
 		} while (list_empty(&dentry->d_subdirs));
 
 		dentry = list_entry(dentry->d_subdirs.next,
 				    struct dentry, d_u.d_child);
 	}
-out:
-	/* several dentries were freed, need to correct nr_dentry */
-	spin_lock(&dcache_lock);
-	dentry_stat.nr_dentry -= detached;
-	spin_unlock(&dcache_lock);
 }
 
 /*
@@ -830,14 +837,15 @@ resume:
 		struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
 		next = tmp->next;
 
-		dentry_lru_del_init(dentry);
 		/* 
 		 * move only zero ref count dentries to the end 
 		 * of the unused list for prune_dcache
 		 */
 		if (!atomic_read(&dentry->d_count)) {
-			dentry_lru_add_tail(dentry);
+			dentry_lru_move_tail(dentry);
 			found++;
+		} else {
+			dentry_lru_del(dentry);
 		}
 
 		/*
@@ -900,12 +908,16 @@ EXPORT_SYMBOL(shrink_dcache_parent);
  */
 static int shrink_dcache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
 {
+	int nr_unused;
+
 	if (nr) {
 		if (!(gfp_mask & __GFP_FS))
 			return -1;
 		prune_dcache(nr);
 	}
-	return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure;
+
+	nr_unused = percpu_counter_sum_positive(&nr_dentry_unused);
+	return (nr_unused / 100) * sysctl_vfs_cache_pressure;
 }
 
 static struct shrinker dcache_shrinker = {
@@ -972,9 +984,10 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
 	spin_lock(&dcache_lock);
 	if (parent)
 		list_add(&dentry->d_u.d_child, &parent->d_subdirs);
-	dentry_stat.nr_dentry++;
 	spin_unlock(&dcache_lock);
 
+	percpu_counter_inc(&nr_dentry);
+
 	return dentry;
 }
 EXPORT_SYMBOL(d_alloc);
@@ -1478,33 +1491,26 @@ out:
  * This is used by ncpfs in its readdir implementation.
  * Zero is returned in the dentry is invalid.
  */
- 
-int d_validate(struct dentry *dentry, struct dentry *dparent)
+int d_validate(struct dentry *dentry, struct dentry *parent)
 {
-	struct hlist_head *base;
-	struct hlist_node *lhp;
+	struct hlist_head *head = d_hash(parent, dentry->d_name.hash);
+	struct hlist_node *node;
+	struct dentry *d;
 
 	/* Check whether the ptr might be valid at all.. */
 	if (!kmem_ptr_validate(dentry_cache, dentry))
-		goto out;
-
-	if (dentry->d_parent != dparent)
-		goto out;
+		return 0;
+	if (dentry->d_parent != parent)
+		return 0;
 
-	spin_lock(&dcache_lock);
-	base = d_hash(dparent, dentry->d_name.hash);
-	hlist_for_each(lhp,base) { 
-		/* hlist_for_each_entry_rcu() not required for d_hash list
-		 * as it is parsed under dcache_lock
-		 */
-		if (dentry == hlist_entry(lhp, struct dentry, d_hash)) {
-			__dget_locked(dentry);
-			spin_unlock(&dcache_lock);
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(d, node, head, d_hash) {
+		if (d == dentry) {
+			dget(dentry);
 			return 1;
 		}
 	}
-	spin_unlock(&dcache_lock);
-out:
+	rcu_read_unlock();
 	return 0;
 }
 EXPORT_SYMBOL(d_validate);
@@ -1994,7 +2000,7 @@ global_root:
  * Returns a pointer into the buffer or an error code if the
  * path was too long.
  *
- * "buflen" should be positive. Caller holds the dcache_lock.
+ * "buflen" should be positive.
  *
  * If path is not reachable from the supplied root, then the value of
  * root is changed (without modifying refcounts).
@@ -2006,10 +2012,12 @@ char *__d_path(const struct path *path, struct path *root,
 	int error;
 
 	prepend(&res, &buflen, "\0", 1);
+	spin_lock(&dcache_lock);
 	error = prepend_path(path, root, &res, &buflen);
+	spin_unlock(&dcache_lock);
+
 	if (error)
 		return ERR_PTR(error);
-
 	return res;
 }
 
@@ -2419,6 +2427,9 @@ static void __init dcache_init(void)
 {
 	int loop;
 
+	percpu_counter_init(&nr_dentry, 0);
+	percpu_counter_init(&nr_dentry_unused, 0);
+
 	/* 
 	 * A constructor could be added for stable state like the lists,
 	 * but it is probably not worth it because of the cache nature